Achieving Optical Gain of the CsPbBr(3) Perovskite Quantum Dots and Influence of the Variable Stripe Length Method

[Image: see text] High-quality inorganic cesium lead halide perovskite quantum dot (CsPbBr(3) PQD) thin films were successfully deposited directly from a powdered source and used as an active laser medium following the examination of their distinctive surface and structural properties. To determine the suitability of the CsPbBr(3) PQDs as an active laser medium, amplified spontaneous emission (ASE) and optical gain properties were investigated under picosecond pulse excitation using the variable stripe length (VSL) method. The thin film of CsPbBr(3) PQDs has exhibited a sufficient value of the optical absorption coefficient of ∼0.86 × 10(5) cm(–1) near the band edge and a direct band gap energy E(g) ∼2.38 eV. The samples showed enhanced emission, and ASE was successfully recorded at a low threshold. The light emitted from the edge was observed near 2.40 and 2.33 eV for the stimulated emission (SE) and ASE regimes, respectively. The nonradiative decay contributes excitons dominant over biexcitons in the sample edge emission above the ASE threshold, making it practical for CsPbBr(3) PQDs to be used as optical gain media without undergoing repeated SE processes above the threshold over long periods. A high value of the optical gain coefficient was recorded at 346 cm(–1).